Hold-down and bearing device for industrial trucks



March 29, 1955 F ND 2,705,084

HOLD-DOWN AND BEARING DEVICE FOR INDUSTRIAL 'mucxs Filed April so, 1953 020092101: Ca e/(4 film/0N0,

United States Patent HOLD-DOWN AND BEARING DEVICE FOR INDUSTRIAL TRUCKS Clark A. Willfond, Gary, Ind., assignor to United States Steel Corporation, a corporation of New Jersey Application April 30, 1953, Serial No. 352,111

3 Claims. (Cl. 214-654) The present invention relates to a bearing device for a hold-down arm and more particularly to an oscillating bearing pad for the hold-down arm of a tractor engaged in transporting piles of sheet material.

The invention finds practical application in the transportation of stacks or piles of sheared tin coated sheets from a processing line to the assortmg room, and n application I shall, in an exemplary way, describe it. In the manufacture of sheared tin coated sheets, the sheets are evenly stacked on wooden skids or platforms as they are discharged from the processing line and the loaded skids are then transported to the assorting room by means of tractors provided with forward extending, vertically adjustable forks which are adapted to support a skid of piled sheets for transporting. The tractors are fitted with hold-down arms which cooperate w th the forks to hold the pile of sheets under compressive force as it is being carried to prevent dislodgment of the sheets or collapse of the pile as the tractor travels over the uneven mill floor.

Prior to my invention, the bearing end of the holddown arm was provided with a rigid bearing block wh ch clamped against the top sheet of the pile being carried when the hold-down arm was swung into operating position. Even though the pile was thus held under compressive force, frequently, a certain amount of shiftmg of the pile occurred which caused the sheets in the top portion of the pile subjacent the top sheet to slide on each other. Contributing factors responsible for this shifting in the pile included, among other things, the vibration caused by the non-rigidity of the hold-down arm and its attachment to the tractor, unevenness of the mill floor, starting and stopping in transit, and, most pertinent, the conventional rigid bearing block which could not compensate for shifting of the stack while in transit. When the sheets in the pile rubbed against each other as the pile shifted, although such relative movement between the sheets was only slight, the sliding sheets abraded each other and were scratched and consequently had to be scrapped.

It is, accordingly, an object of my invention to provide a bearing device for an industrial tractor hold-down arm which is capable of oscillating with the shifting movement of a load being carried by the tractor.

This and other objects will become more apparent after referring to the following specification and attached drawings, in which:

Figure 1 is an elevational view showing a tractor hold-down arm equipped with the bearing of my mvention;

Figure 2 is a plan view of the bearing of my mvention;

Figure 3 is a sectional view taken on the line IlI-Ill of Figure 2;

Figure 4 is a cross-sectional view taken on the line IV-IV of Figure 3; and

Figure 5 is a view similar to Figure 3 showing the bearing of my invention in shifted position.

Referring more particularly to the drawings, reference numeral 2 designates a conventional industrial fork type tractor having a pair of spaced fork elements 4 and a hold-down arm 6. The fork elements and the holddown arm are mounted in spaced relation on a support member 8 which is slidably contained in the vertical guideway 10 of the tractor. The support member 8 is vertically adjustable at the discretion of the tractor operator by means of conventional mechanism. The holddown arm 6 is mounted, at one end, on the support member 8 by suitable means, not a part of this invention, whereby the arm may be swung in an are into clamping position to hold down a pile of sheets S supported on a skid P carried on the fork elements of the tractor. All of the above described features forming no part of the present invention.

The bearing device of my invention, which I have designated generally by the reference numeral 12, is pivotally mounted on the free end of the hold-down arm 6 and engages the top of the pile of sheets S when the hold-down arm is in clamping position as shown in Figure 1.

The main portion of the bearing device 12 is made up of an open top housing 14 having flanged side walls 16, a vertical wall 18 at its forward end, and a vertical wall 20 having a hollow protuberance 22 projecting outwardly therefrom at its rearward end. The inner end 24 of the protuberance is open while its outer end 26 is closed.

An oscillating bearing frame 28, which may be mounted on wheels or bearings 30, is contained within the housing with the wheels 30 rotatively fitted under the flanges of the side wall at each side of the frame. Thus the flanges of the side walls function to provide a track for the wheels and to retain the frame within the housing. A pair of integral spaced bracket projections 32 project upwardly from the frame and the open top of the housing to a pivotal attachment with a transverse pin or bar 34 carried by the free end of the hold-down arm 6.

A pin 36, which may be integral, projects from the rearward end of the frame in line with the open end of the protuberance 22. A helical tension spring 40 is circumferentially disposed on the pin 36 and extends into the protuberance 22. As best shown in Figures 3 and 5, the spring bears against the frame at one end and against the closed end wall of the protuberance at its other end to urge the frame against the forward end wall 18. The pin 36 is adapted to fit slidingly within the protuberance.

A cushion pad 42 of rubber or other suitable resilient material is afiixed to the bottom of the housing 14 by means of set screws 44 to prevent scratching of the top sheet of the pile when the bearing device 12 is clamped thereagainst.

In operation, the tractor is manipulated by the operator so that the fork elements 4 are positioned between the runners on the underside of the skid P on which the pile of sheets S is evenly stacked, whereupon the fork elements are raised and the hold-down arm 6 is swung downwardly to engage the top of the pile S with the bearing device 12 and hold the pile and skid clamped on the fork elements 4. After the skid P has been raised a suitable distance from the mill floor, the tractor is operated to transport the loaded skid to the asserting room. In the asserting room, the supporting member 8 is raised and the skid is deposited upon an assorting table after whichthe hold-down arm is raised out of clamping position and the forks of the tractor withdrawn from underneath the skid.

During transit, the pile of sheets usually shifts slightly in a forward direction by its own momentum due to the slight hesitation of the forward movement of the tractor as it travels over the rough mill floor or stopping and starting of the tractor. As the pile shifts, the housing of my invention shifts with it thereby preventing shifting of the individual sheets in the pile relative to each other and thus eliminating damaging scratches. The relative position of the elements of my bearing device after the load has shifted is best shown in Figure 5. If the bearing on the hold-down arm were rigid, the shifting of the pile would cause the sheets in the upper portion of the pile subjacent the top sheet to slide progressively decreasing amounts from the top of the pile down.

As the pile of sheets S shifts in transit and the housing shifts therewith relative to the frame 28, the pin 36 enters the protuberance 22 thereby compressing the spring 40. When the hold-down arm is swung out of clamping position after the load has been transported to its destination, the spring 40 is released from compression and reestablishes the initial relative positions of the frame and the housing as shown in Figure 3.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a hold-down arm for holding a pile of sheet material under compressive force while being transported the combination therewith of an oscillatable bearing device adapted to engage the top sheet of said pile and shift therewith as said pile shifts in transit; said bearing device comprising a housing having an open top, a bottom, end walls, and flanged side walls; a frame mounted within said housing for oscillating movement relative thereto between said end walls; the flanges on said side wall extending over the sides of said frame to retain the same within said housing; one of said end walls having a hollow protuberance extending outwardly therefrom; the end of the protuberance adjacent said frame being open; a pin projecting from the end of said frame adjacent said protuberance; said pin being adapted to fit into said protuberance; a helical spring circumferentially mounted on said pin and extending therefrom into said protuberance; one end of said spring bearing against said frame and the other end bearing against the closed end of said protuberance; a portion of said frame projecting upwardly from said housing to a pivotal attachment with said hold-down arm; and a resilient cushion pad on the bottom of said housing for engaging the top sheet of said pile.

2. Apparatus for holding a pile of sheets under compressive force while being transported comprising means for supporting said pile of sheets, a hold-down arm extending over said supporting means above said pile of sheets, a frame, means pivotally connecting said frame to the end of said arm for movement in a vertical plane in the direction of movement of the sheets, a housing supported by said frame for reciprocating movement in a substantially horizontal plane in the direction of movement of the sheets, a resilient pad fastened to the bottom of said housing for engaging the top sheet of said pile, means limiting the amount of travel of said housing, and resilient means normally urging the housing to its rearmost position with respect to said frame.

3. Apparatus for holding a pile of sheets under compressive force while being transported as defined by claim 2 characterized by said housing having spaced apart top and bottom abutments, said frame having a portion adapted to engage the top abutments and rotatable wheels adapted to engage said bottom abutment, the distance between the top and bottom abutments being slightly greater than the distance between the top of said portion and the bottom of said wheels.

References Cited in the file of this patent UNITED STATES PATENTS Re. 18,737 Remde Feb. 14, 1933 1,439,227 Cochran Dec. 19, 1922 1,485,818 Schroeder Mar. 4, 1924 2,515,918 Weeks et al. July 18, 1950 2,520,564 Reagle Aug. 29, 1950 2,557,395 Schmidgall June 19, 1951 

